Method, apparatus, system, method and device for data creating, and program for mounting electronic component

ABSTRACT

This invention provides an electronic component mounting method capable of effectively utilizing a self-alignment effect even if a mounting interval of electronic components is small. This method includes the steps of detecting a printing position of a solder paste on the circuit board and mounting an electronic component. This invention further provides apparatus, devices, and system using the method. When a solder paste on a circuit board having a land formed thereon is printed and an electronic component is mounted, the printing position of the solder paste of the circuit board is detected by a printing position detecting device included in an inspecting apparatus. Then, the electronic component is mounted by using the detected printing position of the solder paste as a reference by an electronic component mounting apparatus.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electronic component mounting methodand apparatus for mounting an electronic component on a circuit boardwith high precision, an electronic component mounting system, anelectronic component mounting data creating method, a mounting datacreating device, and a program to be used therein. More particularly,the invention relates to a technique for carrying out mounting byeffectively utilizing a self-alignment effect without a failure inmounting even if there is a small interval between mounting positions ofelectronic components on the circuit board.

2. Description of the Related Art

As shown in FIG. 29, for example, the process for manufacturing acircuit board on which an electronic component mounted includes threesteps. The first step is a printing step (1) of printing a solder pasteon a circuit board having a land formed thereon by means of a solderpaste printing apparatus. The next step is an inspecting step (2) ofinspecting the print state of the solder paste by means of a inspectingapparatus. The last is a mounting step (3) of mounting an electroniccomponent on the circuit board by means of an electronic componentmounting apparatus. The solder paste printing apparatus, the inspectingapparatus and the electronic component mounting apparatus are connectedin this order over a manufacturing line respectively, and the circuitboard fed to the manufacturing line is taken out through the steps (1),(2) and (3) and is sent to a reflow step which is not shown.

Recently, a mounting interval between electronic components to bemounted on a circuit board is reduced to approximately 0.15 mm and thesame interval will tend to be reduced increasingly in the future. Inorder to reduce an interval between components to be mounted, thesoldering state of the electronic component has been fillet-less. Inorder to make the state fillet-less, it is necessary to prevent“extension wetting” in which a molten solder overflows and occurs“solder elevation” along the end face of the terminal of the electroniccomponent as shown in FIG. 30(b). The “solder elevation” is a phenomenonthat a molten solder paste trickles upward along a electronic componentwhen the electronic component is mounted on the solder paste. The“solder elevation” causes the “extension wetting” which causesgeneration of bridges between electronic components. Therefore, thewidth of a land to be formed on the circuit board is set to be equal toor smaller than the width of the terminal of the electronic componentsuch that the overflowed solder does not pollute the end face of theterminal. More specifically, an excessive solder does not stick to theend face of the terminal by setting the width of the land to be equal toor smaller than the width of the terminal of the electronic component.Consequently, it is possible to prevent the solder from extensivelyoverflowing from a terminal surface on the land side.

When an electronic component is to be soldered to the land, a solderpaste is printed on the land and the electronic component is mounted inalignment with the position of the land, and a reflow process is thencarried out. By the reflow process, the solder paste interposed betweenthe land and the terminal of the electronic component is molten andfluidized. The electronic component is also moved to the center positionof the land by a self-alignment effect. Consequently, mounting iscarried out while positioning of the land is performed.

In the conventional soldering method, however, the mounting is carriedout with a target mounting position of the electronic component inalignment with the position of the land. Therefore, in the case in whichthe printing position of the solder paste is shifted from the positionof the land, there is a problem in that a failure in soldering isoccurred after the reflow process. FIG. 31(a) shows a state in which theelectronic component is mounted, in alignment with the center positionof each land, on the circuit board having the solder paste printed witha shift from the position of the land. FIG. 31(b) shows a resultobtained by carrying out the reflow process over the circuit board.

In the case in which a positional relationship between the mountedelectronic component and the printed solder paste is such that thesolder paste is protruded from the end of the electronic component asshown, “extension wetting” is occurred between the solder and the end ofthe electronic component during the reflow process. As a result, thesolder unnecessarily floods over the side surface of the terminal of theelectronic component so that a bridge is generated between the adjacentelectronic components or terminals. The bridge is not generated if themounting interval between the electronic components is wide. However,the bridges are generated frequently in the circuit board having smallintervals between the electronic components particularly that causes aremarkable decline in quality of the circuit board on which is mountedelectronic components.

Moreover, a solder paste printing apparatus can finely control theposition of a land of a circuit board and a printing position of solderpaste. However, it is hard to uniformly carry out alignment over thewhole circuit board having small mounting internals of electroniccomponents, and substantially, it is very hard to completely correct alocal shift.

SUMMARY OF THE INVENTION

The invention has been made in consideration of such conventionalproblems. In order to solve the problems, the invention provides anelectronic component mounting method and device, an electronic componentmounting system, an electronic component mounting data creating method,a mounting data creating device, and a program to be used therein whichcan effectively utilize a self-alignment effect even if the mountinginterval of an electronic component is small.

In order to solve the problems, a first aspect of the invention isdirected to an electronic component mounting method for printing asolder paste on a circuit board including a land formed on the circuitboard and for mounting an electronic component. The method includes thesteps of detecting a printing position of the solder paste on thecircuit board and mounting the electronic component by referring to theprinting position of the solder paste.

In the electronic component mounting method, the printing position ofthe solder paste of the circuit board is detected at the printingposition detecting step and the electronic component is mounted by usingthe detected printing position of the solder paste as a reference at themounting step. Consequently, when the solder paste is molten by a reflowprocess, a self-alignment effect, which is being returned the electroniccomponent to the position of the land by the fluidization of the solderpaste, can be maintained to be great. Therefore, the electroniccomponent can be reliably fixed into the land position even if theprinting position of the solder paste is shifted from the position ofthe land. Also in the case in which the mounting interval of theelectronic component is small, moreover, it is possible to enhanceprecision in the mounting position of the electronic component byeffectively utilizing the self-alignment effect.

A second aspect of the invention is directed to the electronic componentmounting method, wherein a detected result of the printing position ofthe solder paste, which is an output at the printing position detectingstep, is subjected to a feed-forward control to the mounting step,thereby mounting an electronic component.

In the electronic component mounting method, the detected result of theprinting position, which is an output of the printing position detectingstep, is feed-forward controlled form the printing position detectingstep to the mounting step. Consequently, a targeted mounting position ofthe electronic component can be instantaneously set to be a solder pasteprinting position reference for the circuit board to be an object fordetecting the solder paste printing position so that the electroniccomponent can be mounted with an enhancement in the self-alignmenteffect.

A third aspect of the invention is directed to the electronic componentmounting method, wherein a target mounting position of each electroniccomponent is individually set based on a shift amount between a positionof a land corresponding to the electronic component to be mounted and aprinting position of the solder paste for the land.

In the electronic component mounting method, the shift amount betweenthe position of the land corresponding to the electronic component andthe printing position of the solder paste for the land is obtained foreach electronic component. Then, the target mounting position of theelectronic component is individually set based on the shift amountobtained. Consequently, an optimum target mounting position for eachelectronic component can be set and mounting precision can be enhanced.

A fourth aspect of the invention is directed to the electronic componentmounting method, wherein a shift amount between a position of a landcorresponding to the electronic component to be mounted and the printingposition of the solder paste for the land is obtained for all theelectronic components to be mounted on the circuit board, and a targetmounting position of each of the electronic components is collectivelyset based on an added average value of the shift amounts thus obtained.

In the electronic component mounting method, the shift amount betweenthe position of the land corresponding to the electronic component to bemounted and the printing position of the solder paste is obtained forall the electronic components. Then, the added average value of theshift amounts obtained is calculated. The added average value of theshift amounts is applied to all the electronic components of the circuitboard to collectively set the target mounting position of eachelectronic component. Consequently, the target mounting position can beset simply and a time required for calculation can be shortened.

A fifth aspect of the invention is directed to the electronic componentmounting method, wherein the circuit board is divided into a pluralityof blocks and a shift amount between a position of a land correspondingto an electronic component to be mounted in each block and the printingposition of the solder paste for the land is obtained. Then, a targetmounting position of the electronic component is set for each blockbased on the shift amount thus obtained.

In the electronic component mounting method, the circuit board isdivided into a plurality of blocks and the shift amount between theposition of the land corresponding to the electronic component to bemounted in each block and the printing position of the solder paste isobtained. Based on the shift amount of each block thus obtained, thetarget mounting position of the electronic component is set for eachblock. Consequently, even if the shift amount tends to be varied foreach block, a proper target mounting position can be set in each block.Moreover, it keeps a region having a small shift from being influencedby a region having a great shift and it is possible to prevent the shiftfrom an original target mounting position of the region having the smallshift from being increased. Thus, the self-alignment effect can beuniformly obtained over the whole circuit board and the mounting can becarried out with high precision in alignment.

A sixth aspect of the invention is directed to the electronic componentmounting method, wherein the blocks are obtained by an annular divisionfrom a peripheral edge of the circuit board toward a center.

In the electronic component mounting method, the division is annularlycarried out from the peripheral edge of the circuit board toward thecenter, thereby forming the blocks. Consequently, in the case in whichthe center of the circuit board has a small shift amount and the shiftamount tends to be increased toward the peripheral edge, for example, itis possible to correct the target mounting position slightly on thecenter of the circuit board and greatly toward the peripheral edge.Thus, it is possible to uniformly obtain the self-alignment effect overthe whole circuit board.

A seventh aspect of the invention is directed to the electroniccomponent mounting method, wherein the block is obtained by dividing thecircuit board like a lattice.

In the electronic component mounting method, the circuit board isdivided into blocks like a lattice. Consequently, in the case in whichthe shift amount of the corner portion of the circuit board is small andtends to be increased apart from the corner portion, for example, it ispossible to correct the target mounting position slightly in the cornerportion and greatly apart from the corner portion. Thus, theself-alignment effect can be uniformly obtained over the whole circuit.

An eighth aspect of the invention is directed to the electroniccomponent mounting method, wherein a self-alignment effect is decidedfrom a shift state between a position of a land corresponding to theelectronic component to be mounted and the printing position of thesolder paste for the land. Then, a target mounting position of theelectronic component is set by using the printing position of the solderpaste as a reference when the self-alignment effect is great, while thetarget mounting position is set by using the position of the land as thereference when the self-alignment effect is small.

In the electronic component mounting method, the self-alignment effect,which can be expected by mounting the electronic component, is decidedbased on the shift state between the position of the land and theprinting position of the solder paste. And then, the target mountingposition of the electronic component is set by using the printingposition of the solder paste as a reference when the self-alignmenteffect is great, while the target mounting position is set by using theposition of the land as a reference when the self-alignment effect issmall. Consequently, it is possible to properly change the targetmounting position corresponding to the self-alignment effect which canbe expected. Moreover, it is possible to carry out the mounting suchthat the electronic component can always be fixed into the land positionafter the reflow process of the circuit board.

A ninth aspect of the invention is directed to the electronic componentmounting method, wherein a correction value is set at an optional ratefor a shift amount between a position of a land corresponding to theelectronic component to be mounted and the printing position of thesolder paste for the land. Then, the target mounting position of theelectronic component is changed from the position of the land toward theprinting position of the solder paste based on the correction value thusset.

In the electronic component mounting method, the correction value is setin an optional ratio of 50%, 80% or 100%, for example, with respect tothe shift amount between the position of the land and the printingposition of the solder paste. Therefore, the target mounting position ofthe electronic component is changed from the position of the land towardthe printing position of the solder paste based on the correction valuethus set. The self-alignment effect to be changed on fine conditions canbe maintained to be optimum and the electronic component can be mountedwith much higher precision.

A tenth aspect of the invention is directed to the electronic componentmounting method, wherein the correction value is set based on a degreeof the self-alignment effect. The self-alignment is determined dependingon a shift state of the position of the land corresponding to anelectronic component to be mounted from the printing position of thesolder paste for the land.

In the electronic component mounting method, the correction value is setdepending on the degree of the self-alignment effect determined by theshift state of the position of the land from the printing position ofthe solder paste. Consequently, the correction value can be directlyreflected by the self-alignment effect so that the electronic componentcan be mounted with much higher precision.

An eleventh aspect of the invention is directed to the electroniccomponent mounting method, wherein the correction value is set dependingon a characteristic of a solder paste to be used.

In the electronic component mounting method, the correction value is setdepending on the characteristic of the solder paste to be used.Consequently, it is possible to set a proper correction valuecorresponding to various conditions such as a material composition, africtional characteristic or a viscosity of the solder paste.

A twelfth aspect of the invention is directed to the electroniccomponent mounting method, wherein when the electronic componentinterferes with adjacent other electronic components over the circuitboard during mounting of the electronic component on the circuit board,a mounting operation for the electronic component is not carried out.

In the electronic component mounting method, when mounting theelectronic component to which the target mounting position is set byusing the printing position of the solder paste as a reference, themounting operation for the electronic component is not carried out overthe electronic component which interferes with adjacent other electroniccomponents on the circuit board. Consequently, it prevents fromoccurring a failure in mounting beforehand. Moreover, it is possible toprevent the productivity of the circuit board from deteriorating.

A thirteenth aspect of the invention is directed to the electroniccomponent mounting method, wherein when the electronic componentinterferes with adjacent other electronic components over the circuitboard during mounting of the electronic component on the circuit board,a target mounting position of the electronic component to be mounted ischanged from a printing position of a solder paste toward a position ofa land to a position in which the interference is not present.

In the electronic component mounting method, when the electroniccomponent interferes with the other electronic components during themounting, the target mounting position of the electronic component to bemounted is changed from the printing position of the solder paste towardthe position of the land to a position in which the interference is notpresent. Thus, it is possible to mount the electronic component withoutstop while maintaining the self-alignment effect to be required.Consequently, it is possible to prevent a recovery process from beingcarried out due to the stop of the mounting of the electronic component,and the mounting step can be thus carried out more quickly.

A fourteenth aspect of the invention is directed to the electroniccomponent mounting method, wherein when a shift amount between aposition of a land corresponding to the electronic component to bemounted and a printing position of a solder paste for the land exceeds apredetermined shift amount, a shift amount in a direction of rotation isobtained in addition to a shift amount in a horizontal direction. Then,a target mounting position and a target rotating angle of the electroniccomponent are set based on the shift amounts in the horizontal directionand the direction of rotation.

In the electronic component mounting method, when the shift amount ofthe position of the land from the printing position of the solder pasteexceeds a predetermined shift amount, both of the shift amount in thedirection of rotation and in the horizontal direction are obtained.Then, the target mounting position and the target rotating angle of theelectronic component are set based on the shift amounts in thehorizontal direction and the direction of rotation. Consequently, it ispossible to set the target mounting position and the target rotatingangle from which a desired self-alignment effect can be obtained withhigh precision, and mounting precision can be thus enhanced.

A fifteenth aspect of the invention is directed to the electroniccomponent mounting method, wherein the printing position detecting stepincludes the steps of picking up an s image of a circuit board printed asolder paste, reproducing a shape of a land hidden in the solder pasteof the image picked up by interpolating with previously registered landdata, and obtaining a center of a position of the land from the shape ofthe land thus reproduced.

In the electronic component mounting method, the printing positiondetecting step picks up an image of a circuit board having a solderpaste printed thereon, reproduces a shape of a land hidden in the solderpaste of the image picked up by interpolating with previously registeredland data, and obtains a center of a position of the land from the shapeof the land thus reproduced. Consequently, also in the case in which thecomplete shape of the land cannot be visually recognized, the shape ofthe land can be reproduced by using the land data and the center of theposition of the land can be obtained accurately.

A sixteenth aspect of the invention is directed to an electroniccomponent mounting apparatus for mounting an electronic component on acircuit board having a solder paste printed for a land, wherein theelectronic component is mounted on the circuit board by using, as areference, a printing position of the solder paste of the circuit board.

In the electronic component mounting apparatus, the mounting position ofthe electronic component is corrected by using, as a reference, theprinting position of the solder paste on the detected circuit board.Thereby, the electronic component mounting apparatus carries out themounting. Consequently, when the solder paste is molten by the reflowprocess, the self-alignment effect of returning the electronic componentinto the position of the land by the fluidization of the solder pastecan be maintained to be great. Also in the case in which the printingposition of the solder paste is shifted from the position of the land,the electronic component can be reliably fixed into the position of theland. Also in the case in which the mounting interval between theelectronic components is small, moreover, the precision in the mountingposition of the electronic component can be enhanced by effectivelyutilizing the self-alignment effect.

A seventeenth aspect of the invention is directed to the electroniccomponent mounting apparatus, wherein mounting data for mounting anelectronic component on a circuit board are created based on theelectronic component mounting method according to any of the first tofifteenth aspects.

In the electronic component mounting apparatus, the mounting data formounting the electronic component on the circuit board are created bythe electronic component mounting apparatus. Consequently, the mountingdata can be created by means of minimum equipment.

An eighteenth aspect of the invention is directed to an electroniccomponent mounting system for printing a solder paste on a circuit boardhaving a land formed on the circuit board and mounting an electroniccomponent based on the electronic component mounting method according toany of the first to fifteenth aspects, including a printing positiondetecting device for detecting a printing position of the solder pasteof the circuit board, and an electronic component mounting apparatus formounting an electronic component based on a result of detection of theprinting position.

The electronic component mounting system includes a printing positiondetecting device for detecting a printing position of the solder pasteof the circuit board, and an electronic component mounting apparatus formounting an electronic component based on a result of detection of theprinting position. The electronic component is mounted by using theprinting position of the solder paste as a reference. Consequently, whenthe solder paste is molten by the reflow process, the self-alignmenteffect of returning the electronic component into the land position bythe fluidization of the solder paste can be maintained to be great. Alsoin the case in which the printing position of the solder paste isshifted from the position of the land, the electronic component can bereliably fixed into the position of the land. Also in the case in whichthe mounting interval between the electronic components is small,moreover, the precision in the mounting position of the electroniccomponent can be enhanced by effectively utilizing the self-alignmenteffect.

A nineteenth aspect of the invention is directed to the electroniccomponent mounting system, further including a solder paste printingapparatus for printing a solder paste on a circuit board having a landformed thereon by setting a position of the land to be a targetposition.

The electronic component mounting system includes a solder pasteprinting apparatus for printing a solder paste on a circuit board havinga land formed thereon by setting a position of the land to be a targetposition. Therefore, it is possible to consistently carry out a seriesof processes from the printing of the solder paste to the mounting ofthe electronic component and to quickly feed back the print shift of thesolder paste detected by the printing position detecting device to thesolder paste printing step for another circuit board.

A twentieth aspect of the invention is directed to the electroniccomponent mounting system, wherein the printing position detectingdevice is constituted integrally with the solder paste printingapparatus.

In the electronic component mounting system, the printing positiondetecting device is constituted integrally with the solder pasteprinting apparatus. Consequently, an installation space can be reducedand a process for delivering the circuit board can be simplified so thata high-speed process can be carried out still more.

A twenty-first aspect of the invention is directed to the electroniccomponent mounting system, wherein the printing position detectingdevice is constituted integrally with the electronic component mountingapparatus.

In the electronic component mounting system, the printing positiondetecting device is constituted integrally with the electronic componentmounting apparatus. Consequently, an installation space can be reducedand a process for delivering the circuit board can be simplified so thata high-speed process can be carried out still more.

A twenty-second aspect of the invention is directed to the electroniccomponent mounting system, further including a host computer connectedto at least the printing position detecting device and the electroniccomponent mounting apparatus through a communication line and serving toreceive a result of detection of a printing position from the printingposition detecting device and to transmit a feed-forward signal to theelectronic component mounting apparatus.

In the electronic component mounting system, at least the printingposition detecting device and the electronic component mountingapparatus are connected to the host computer through the communicationline, and the result of detection of the printing position is input fromthe printing position detecting device to the host computer and thefeed-forward signal is output from the host computer to the electroniccomponent mounting apparatus. Consequently, each apparatus can begenerally managed. Also in the case in which a plurality of electroniccomponent mounting systems are constructed, they can be easily connectedand generally managed.

A twenty-third aspect of the invention is directed to an electroniccomponent mounting data creating method, wherein mounting data formounting an electronic component on a circuit board based on theelectronic component mounting method according to any of the first tofifteenth aspects are created by the electronic component mountingapparatus.

In the electronic component mounting data creating method, mounting datafor mounting an electronic component on a circuit board based on theelectronic component mounting method according to any of the first tofifteenth aspects are created by the electronic component mountingapparatus. Consequently, it is possible to create the mounting data bymeans of minimum equipment.

A twenty-fourth aspect of the invention is directed to an electroniccomponent mounting data creating method, wherein mounting data formounting an electronic component on a circuit board based on theelectronic component mounting method according to any of the first tofifteenth aspects are created by an external device connected to theelectronic component mounting apparatus and the mounting data thuscreated are fetched into the electronic component mounting apparatus.

In the electronic component mounting data creating method, mounting datafor mounting an electronic component on a circuit board based on theelectronic component mounting method according to any of the first tofifteenth aspects are created by an external device connected to theelectronic component mounting apparatus and are then fetched. Even ifthe electronic component mounting apparatus is carrying out the mountingoperation, consequently, the mounting data can be created. Thus,workability for data creation can be enhanced and the operatingefficiency of producing equipment can be increased.

A twenty-fifth aspect of the invention is directed to an electroniccomponent mounting data creating method of creating mounting data formounting an electronic component on a circuit board based on theelectronic component mounting method according to any of the first tofifteenth aspects, wherein a correction amount for changing a targetmounting position of the electronic component from a position of a landtoward a printing position of a solder paste is collectively set basedon a type of the solder paste to be used by utilizing a table previouslyregistering a degree of a self-alignment effect for each type of thesolder paste.

In the electronic component mounting data creating method, thecorrection amount for changing the target mounting position of theelectronic component from the position of the land toward the printingposition of the solder paste is collectively set by referring to thetable based on the type of the solder paste to be used so that theself-alignment effect to be changed depending on various characteristicsof the solder paste is obtained. Consequently, a time and labor forinputting the characteristics one by one can be omitted and the mountingdata can be created easily.

A twenty-sixth aspect of the invention is directed to an electroniccomponent mounting data creating method of creating mounting data formounting an electronic component on a circuit board based on theelectronic component mounting method according to any of the first tofifteenth aspects, wherein a correction amount for changing a targetmounting position of the electronic component from a position of a landtoward a printing position of a solder paste is collectively set basedon an electronic component to be mounted and a type of the solder pasteto be used by utilizing a table previously registering a degree of aself-alignment effect depending on a combination of a type of theelectronic component and that of the solder paste.

In the electronic component mounting data creating method, thecorrection amount for changing the target mounting position of theelectronic component from the position of the land toward the printingposition of the solder paste is collectively set by using the tablebased on the electronic component to be mounted and the type of thesolder paste to be used. Consequently, a time and labor for inputtingvarious self-alignment effects one by one depending on the combinationof the type of the electronic component and the solder paste to be usedand the mounting data can be created easily.

A twenty-seventh aspect of the invention is directed to a mounting datacreating device provided separately from an electronic componentmounting apparatus and serving to create mounting data for mounting anelectronic component on a circuit board based on the electroniccomponent mounting method according to any of the first to fifteenthaspects.

In the mounting data creating device, the mounting data for mounting theelectronic component on the circuit board are created irrespective ofthe electronic component mounting apparatus, and the electroniccomponent mounting apparatus is subsequently caused to fetch themounting data thus created. Consequently, even if the electroniccomponent mounting apparatus is carrying out the mounting operation, themounting data can be created. Thus, workability for data creation can beenhanced and the operating efficiency of producing equipment can beincreased.

A twenty-eighth aspect of the invention is directed to a program inwhich mounting data for mounting an electronic component on a circuitboard based on the electronic component mounting method according to anyof the first to fifteenth aspects are recorded and used for anelectronic component mounting apparatus.

The program recording mounting data for mounting an electronic componenton a circuit board based on the electronic component mounting methodaccording to any of the first to fifteenth aspects is used for anelectronic component mounting apparatus. Consequently, it is possible tomount the electronic component with the self-alignment effect enhanced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view schematically showing the step of printing a solderpaste onto a circuit board having a land formed thereon to the step ofmounting an electronic component.

FIG. 2 is a view showing a positional relationship between the landformed on the circuit board, the printed solder paste and the electroniccomponent to be mounted.

FIG. 3(a), (b) and (c) are views illustrating the self-alignment effectof the mounted electronic component in a P-P section of FIG. 2.

FIG. 4(a), (b) and (c) are views illustrating the self-alignment effectof the mounted electronic component in the P-P section of FIG. 2.

FIG. 5 is a perspective view showing the appearance of a printer, a partof which is taken away.

FIG. 6 is a view showing the detailed structure of a table portion.

FIG. 7 is a perspective view showing a print unit, a part of which is asection.

FIG. 8 is a perspective view showing the appearance of the structure ofa inspecting apparatus, a part of which is taken away.

FIG. 9 is a perspective view showing an electronic component mountingapparatus.

FIG. 10 is an enlarged perspective view showing the transfer head of theelectronic component mounting apparatus,

FIG. 11 is a block diagram showing the structure of a control device forcontrolling the electronic component mounting apparatus.

FIG. 12 is a block diagram showing the structure of mounting data to beused in the electronic component mounting apparatus.

FIG. 13 is a flow chart showing the procedure for changing the targetmounting position of an electronic component from the position of a landto be usually used to the printing position of a solder paste,

FIG. 14 is a view schematically illustrating the contents of checkobtained by the inspecting apparatus.

FIG. 15 is a diagram illustrating a state in which the central positionof the shape of a land is to be measured.

FIG. 16 is a view illustrating center-of-gravity positions O_(C1) andO_(C2) of the solder paste printed on the circuit board and shiftamounts α and β in X and Y directions,

FIG. 17 is a view illustrating a shift amount =74 in the direction ofrotation of the solder paste printed on the circuit board,

FIG. 18(a) and FIG. 18 (b) show patterns for dividing the circuit boardinto the optional number of blocks. FIG. 18(a) shows an example in whichthe circuit board is annularly divided into regions from the peripheraledge of the circuit board toward a center and FIG. 18(b) showing anexample in which the circuit board is divided into regions like alattice.

FIG. 19 is a diagram showing a table for various parameters of theweight and shape of the electronic component to be mounted and thesolder paste to be used. FIG. 19 also shows the combination of the typeof the electronic component to be actually used and the material of thesolder paste by utilizing the table.

FIG. 20(a) and FIG. 20(b) show states in which the solder paste isprinted into the position of a land. FIG. 20(a) shows a state in whichthe solder paste is printed with a shift from the center of the land.FIG. 20(b) shows a state in which the solder paste is printed with aprotrusion from the land.

FIG. 21 is a flow chart according to a fifth embodiment of an electroniccomponent mounting method in accordance with the invention.

FIG. 22 is a view showing a state in which adjacent electroniccomponents interfere with each other.

FIG. 23 is a view showing an example of a structure according to a firstvariant of an electronic component mounting system for implementing theelectronic component mounting method according to each embodiment. FIG.24 is a view showing an example of a structure according to a secondvariant of the electronic component mounting system for implementing theelectronic component mounting method according to each embodiment.

FIG. 25 is a view showing an example of a structure according to a thirdvariant of the electronic component mounting system for implementing theelectronic component mounting method according to each embodiment.

FIG. 26 is a view showing the appearance of an electronic componentmounting apparatus including a rotary head.

FIG. 27 is a schematic sectional view showing the rotary head forexplaining the operation of the rotary head.

FIGS. 28(a) through 28(c) are diagrams showing results obtained bycomparing self-alignment effects on two conditions.

FIG. 29 is a view showing the step of manufacturing a circuit boardmounted on an electronic component according to a conventional art.

FIG. 30(a) and FIG. 30(b) are views for explanation how “extensionwetting” is occurred. FIG. 30(b) shows a state of “solder elevation” inwhich a molten solder trickles upward along the end face of the terminalof the electronic component.

FIG. 31(a) and FIG. 31(b) are views showing failures in soldering causedby the shift of the printing position of a solder paste. FIG. 31(a)shows a state in which an electronic component is mounted on a circuitboard having a solder paste printed with a shift from the position of aland in alignment with the central position of each land. FIG. 31(b)shows a result obtained by carrying out a reflow process over thecircuit board when the “extension wetting” is occurred.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An electronic component mounting method and apparatus, an electroniccomponent mounting system, an electronic component mounting datacreating method, a mounting data creating device and a program to beused therein according to embodiments of the invention will be describedbelow in detail with reference to the drawings.

FIG. 1 is a view schematically showing a process for printing a solderpaste on a circuit board having a land formed thereon and mounting anelectronic component. In the embodiment, first of all, the circuit boardis fed to a solder paste printing apparatus 100 and the solder paste isprinted corresponding to the position of a land on the circuit board.Then, the land and the solder paste are recognized to inspect a shiftthereof by means of a inspecting apparatus 200 in a latter stage. Theresult of the inspection is transmitted to an electronic componentmounting apparatus 300 in a further latter stage and the circuit boardhaving the solder paste printed thereon is fed to the electroniccomponent mounting apparatus 300. The electronic component mountingapparatus 300 corrects the mounting position of the electronic componentbased on the result of the inspection which is transmitted from theinspecting apparatus 200 with respect to the fed circuit board, and theelectronic component is mounted in the corrected position. The basiccontents of a process for manufacturing the circuit board are describedabove. The invention is characterized in that the electronic componentis mounted by using, as a reference, the printing position of the solderpaste printed on the circuit board. In this specification, the solderpaste implies a paste-like solder obtained by mixing solder powder intoa flux having a high viscosity.

Detailed description will be given to the principle of the electroniccomponent mounting method of mounting an electronic component by using asolder paste printing position as a reference according to theinvention.

FIG. 2 is a view showing a positional relationship between a land formedon a circuit board, a printed solder paste and an electronic componentto be mounted, and FIGS. 3 and 4 are views illustrating theself-alignment effect of the mounted electronic component in a P-Psection of FIG. 2, respectively.

As shown in FIG. 2, solder pastes 16a and 16b are printed on lands 14 aand 14 b formed on a circuit board 12 in a position shifted from a landcenter line L1 by a distance ΔL. In this case, an electronic component18 is mounted in alignment with the positions of the solder pastes 16 aand 16 b and a center line Lc of the solder pastes 16 a and 16 b isalmost coincident with a center line Lp of the electronic component.When the reflow process is carried out in this state, the solder pasteis molten and fluidized over the land. In the early stage of thefluidization, a solder 20 extensively wets due to “immersion wetting”which is generally caused during capillary permeation as shown in FIG.3(a). When the solder 20 extensively wets both end faces 18 a and 18 a′of the electronic component 18 as shown in FIG. 3(b), the “extensionwetting” of the solder on the component end face side is stopped andonly the solder on the land 14 side extensively wets. Consequently, thesolder 20 moves the electronic component 18 in the direction of an arrowto bring a stable state having a dynamic balance. This acts as theself-alignment effect so that the electronic component 18 is finallyprovided in such a position that the center line L1 of the land 14 iscoincident with the center line Lp of the electronic component 18 asshown in FIG. 3(c).

In some cases, moreover, the self-alignment effect acts as shown in FIG.4. When the solder 20 is molten as shown in FIGS. 4(a) and (b), theelectronic component 18 is moved with the “extension wetting” generatedby the “immersion wetting” so that the self alignment effect can beobtained. When the “extension wetting” of the solder 20 over the land 14is completed and the solder 20 is brought into the stable state having adynamic balance as shown in FIG. 4(c), the movement of the electroniccomponent 18 is also stopped. Accordingly, the electronic component 18is finally provided in such a position that the center line L1 of theland 14 is coincident with the center line Lp of the electroniccomponent 18.

According to such a self-alignment effect, in the case in which theelectronic component is to be mounted by setting the land position to bethe target mounting position, a probability that the shift of theelectronic component will be corrected is approximately 50% when a shiftof 50 μm or more is caused, for example. On the other hand, in the casein which the electronic component is to be mounted by setting theposition of the printed solder paste to be the target mounting position,the shift can be corrected with a probability of 80 to 90% by theself-alignment effect even if the shift of 50 μm or more is caused.

Next, description will be given to an example of a structure of theelectronic component mounting system for mounting an electroniccomponent by using the self-alignment effect. The specific structures ofthe solder paste printing apparatus 100, the inspecting apparatus 200and the electronic component mounting apparatus 300 according to theembodiment will be described below.

First of all, the solder paste printing apparatus according to theembodiment (which will be hereinafter referred to as a printer) can havea structure shown in FIG. 5, for example. FIG. 5 is a perspective viewshowing the appearance of the printer 100, a part of which is takenaway. The printer 100 includes a circuit board delivering unit 22 fordelivering the circuit board 12 to be a solder paste printing objectinto and from the printer 100, a table unit 26 for mounting thedelivered circuit board 12 thereon to be moved to the lower surface of aprinting mask 24, and a printing unit 30 for printing the solder pasteby squeegees 28 a and 28 b above the circuit board 12 positioned on thelower surface of the printing mask 24.

According to the printer 100, the circuit board 12 is delivered in thefollowing manner. More specifically, the circuit board delivering unit22 receives the circuit board 12 delivered from a stocker or a line andfeeds the circuit board 12 to the table unit 26 provided in the printer100. The table portion 26 positions and fixes the circuit board 12 thusfed, and moves the circuit board 12 to a predetermined position on thelower surface of the printing mask 24 of the printing unit 30. Moreover,when the printing process of the printing unit 30 is completed, thetable unit 26 delivers the circuit board 12 from the printing unit 30 tothe circuit board delivering portion 22. Then, the circuit boarddelivering unit 22 takes the circuit board 12 from the table unit 26 anddischarges the circuit board 12 to a delivery outlet, which is notshown.

FIG. 6 shows the detailed structure of the table unit 26. The tableportion 26 includes a board mounting table 34 capable of fixing thecircuit board 12 through a holding member 32 and moving and rotating thecircuit board 12 by a motor control in directions of X, Y, Z and θ shownin the drawing, a board recognizing camera 36 for recognizing analignment mark on the circuit board 12, and a mask recognizing camera 38for recognizing an alignment mark on the printing mask 24.

The board recognizing camera 36 picks up the image of the alignment markprovided previously on the circuit board 12 to be a printing objectwhich is fed from the circuit board delivering unit 22 to the table unit26. The image thus picked up is processed to recognize a mark position.Consequently, the position of the circuit board 12 can be managedaccurately and the positioning can be carried out in a predeterminedposition for printing with high precision.

Moreover, the mask recognizing camera 38 picks up the image of thealignment mark provided previously on the printing mask 24. The imagethus picked up is processed to recognize a mark position. Consequently,the circuit board 12 can be positioned with high precision in a properposition corresponding to the perforation pattern of the printing mask24. The circuit board delivering unit 22 and the table unit 26 can beconstituted by using a loader, an unloader and a 4-axis stage which aregenerally used widely.

FIG. 7 is a perspective view showing the printing unit 30, a part ofwhich is a section. The printing unit 30 moves a pair of squeegees 28 aand 28 b in both forward and backward print directions on the upper sideof the printing mask 24 in such a state that the circuit board 12 fixedonto the board mounting base 34 by the holding member 32 is provided onthe lower side of the printing mask 24. Thus, the solder paste isprinted on the circuit board 12. The squeegee 28 a is used during theprinting in the backward direction and the squeegee 28 b is used duringthe printing in the forward direction.

After the solder paste is printed in the position of the land formed onthe circuit board 12 by using the printer 100 having the structuredescribed above, the printed circuit board 12 is taken out of theprinter 100 and is fed to the inspecting apparatus 200 in the latterstage.

Next, the structure of the inspecting apparatus 200 will be described.FIG. 8 is a perspective view showing the appearance of the structure ofthe inspecting apparatus 200, a part of which is taken away. Theinspecting apparatus 200 includes a printing position detecting devicefor detecting the printing position of the solder paste printed on thecircuit board. The inspecting apparatus 200 includes a board deliveringportion 40 for delivering the circuit board 12 thus fed, light sources44 and 44 such as fluorescent lamps for illuminating the circuit board12 stationary in a inspecting unit 42 in an oblique direction, and animage pick-up camera 46 for picking up the image of a board surface fromabove the circuit board 12. In the inspecting apparatus 200, the imageof the circuit board 12 illuminated by the light sources 44 and 44 ispicked up by the image pick-up camera 46 and the image thus picked up isprocessed by a controller (not shown) provided in the inspectingapparatus 200. Consequently, each land of the circuit board 12 and theprinted solder paste are detected to obtain a corresponding shift amountthereof. Information about the shift amount thus obtained is onceretained in the controller and is transmitted as a result of check tothe electronic component mounting apparatus 300 in the latter stage.

Moreover, the result of inspection is fed back to the solder pasteprinting apparatus 100 and the solder paste printing apparatus 100 isregulated to quickly correct the print shift of the solder paste.

Next, the structure of the electronic component mounting apparatus willbe described.

FIG. 9 is a perspective view showing the electronic component mountingapparatus, FIG. 10 is an enlarged perspective view showing the transferhead of the electronic component mounting apparatus, FIG. 11 is a blockdiagram showing the structure of a control device for controlling theelectronic component mounting apparatus, and FIG. 12 is a block diagramshowing the structure of mounting data to be used in the electroniccomponent mounting apparatus.

The structure of the electronic component mounting apparatus 300 will besimply described. As shown in FIG. 9, the electronic component mountingapparatus 300 is provided with a guide rail 52 of the circuit board 12on the center of the upper surface of a base 50, and the circuit board12 is delivered from a board delivery-in unit 54 on one of end sides toa mounting position 56 of the electronic component, and furthermore,from the mounting position 56 to a board delivery-out unit 58 on theother end side through the delivery belt of the guide rail 52.

Y tables 60 and 62 are provided in both side portions of the uppersurface of the base 50 provided above the circuit board 12 respectively,and an X table 64 is provided between the two Y tables 60 and 62.Moreover, a transfer head 66 is attached to the X table 64.Consequently, the transfer head 66 can be moved in an X-Y plane.

The transfer head 66 mounted on an XY robot including the X table 64 andthe Y tables 60 and 62 and movable over the X-Y plane (horizontal plane)is constituted such that a desirable electronic component is heldthrough an suction nozzle 72 from a component feeding member 68 forfeeding an electronic component such as a resistance chip or a chipcapacitor or a component feeding tray 70 for feeding a comparativelylarge-sized electronic component such as an IC, for example, an SOP or aGFP or a connector and the sucking attitude of the electronic componentis detected from a recognizing device 74 and the electronic component isthen mounted in the predetermined position of the circuit board 12. Suchan electronic component mounting operation is controlled based on apreset mounting program (hereinafter referred to as mounting data) bythe control device. Data can be input to the control device through anoperation panel 76.

A large number of component feeding member 68 are arranged on both endsof the guide rail 52 and a tape-shaped component roll accommodating anelectronic component such as a resistance chip or a chip capacitor isattached to each of the component feeding member 68.

Moreover, the component feeding tray 70 can mount two trays 70a in totalwhich are elongated in a direction orthogonal to the guide rail 52, andeach of the trays 70a is so constituted as to slide toward the guiderail 52 side corresponding to the number of components to be fed,thereby maintaining a component take-out position in a Y direction to bea constant position.

The recognizing device 74 for detecting the two-dimensional shift(sucking attitude) of the electronic component held in the suctionnozzle 72 and for correcting the shift on the transfer head 66 side isprovided in the side portion of the circuit board 12 positioned on theguide rail 52. The attitude recognizing camera is provided in a bottomportion on the inside of the recognizing device 74 and a plurality oflight emitting elements such as a light emitting diode LED forilluminating the electronic component held in the suction nozzle 72 areprovided in a multi-stage on the internal surface of a housing aroundthe attitude recognizing camera. Consequently, light can be irradiatedon the mounting surface of the electronic component at a desirable angleand an image can be, picked up at a proper illumination angle accordingto the type of the component. The illumination angle is set for eachelectronic component based on preset data for component recognition.Moreover, the image pick-up data obtained by the recognizing device 74are subjected to a recognition process by the control device, and thecentral position or the electrode position of the electronic componentis recognized and is used for correction data on a mounting position andan angle.

As shown in FIG. 10, the transfer head 66 is constituted as a multiplemulti-head having a plurality of (four in the embodiment) attachmentheads (a first attachment head 78 a, a second attachment head 78 b, athird attachment head 78 c and a fourth attachment head 78 d) coupled ina transverse direction. The four attachment heads 78 a to 78 d have thesame structure and include the suction nozzle 72, an actuator 80 forcausing the suction nozzle 72 to carry out a vertical operation, and amotor 82, a timing belt 84 and a pulley 86 for rotating the suctionnozzle 72 itself.

The suction nozzle 72 of each attachment head is exchangeable and othersuction nozzles are previously accommodated in a nozzle stocker 88provided on the base 50 of the electronic component mounting apparatus300. Examples of the suction nozzle 72 include an S size nozzle forholding a very small chip component having a size of approximately1.0×0.5 mm and an M size nozzle for holding a QFP of 18 mm square whichare selectively used depending on the type of the electronic componentto be attached.

In a block diagram of FIG. 11 showing a main structure, the controldevice includes an I/O processing circuit 90 for digitally converting animage signal sent from the attitude recognizing camera of therecognizing device 74 and fetching the signal thus obtained and forfetching a result of check from the inspecting apparatus 200, amicrocomputer 92 for fetching digital data through the I/O processingcircuit 90 and carrying out various information processings such as animage processing, an image memory 94 for storing image data, and a database 96 storing various mounting data for executing a predeterminedcontrol program. Moreover, the control device includes drivers 99 a to99 d for driving X, Y, Z and θ axes to drive motors 98 a and 98 b forcontrolling X-axis and Y-axis movement of an XY robot shown in FIG. 9 inresponse to an instruction sent from the microcomputer 92, a motor 98 c(an actuator 80) for controlling Z-axis movement for the attachmentheads 78 a to 78 d shown in FIG. 11, and a motor 98 d (motor 82) forcontrolling θ-axis movement.

Furthermore, the control device includes a reading device 112 forreading mounting data for carrying out the mounting operation formounting the electronic component on at least the circuit board 12 froman information storage medium (for example, a magnetic recording medium,a magneto-optic recording medium, an optical recording medium or asolid-state storage element such as a flash memory) 110 storing themounting data. The mounting data may be provided from the informationrecording medium 110 through a network to be a communication line.

The mounting data include an NC program 114 recording information abouta mounting position onto the circuit board 12, a component feedingposition in the component feeding member 68 or the component feedingtray 70, or a mounting order, an array program 116 recording informationabout the arrangement of the electronic component in each componentfeeding position, a component library 118 recording information aboutthe shape of the electronic component, a mark library 120 recordinginformation about the shape of a board mark such as a mark for aligningthe circuit board, and board data 122 recording information about theshape of the circuit board and the shape of a land.

Next, description will be given to the mounting operation to be carriedout by the electronic component mounting apparatus 300 having thestructure described above.

First of all, the circuit board 12 delivered from the inspectingapparatus 200 is fed from the board delivery-in portion 54 of the guiderail 52 into the device and is delivered to the predetermined mountingposition 56. Moreover, the result of inspection, which is transmittedfrom the inspecting apparatus 200, is input to the control device.

Subsequently, the transfer head 66 is moved in the X-Y plane through theXY robot to adsorb and hold a predetermined electronic component fromthe component feeding member 68 or the component feeding tray 70 basedon a preset mounting program. Then, the transfer head 66 is moved ontothe attitude recognizing camera of the recognizing device 74 with theelectronic component held so that the sucking attitude of the electroniccomponent is recognized. Consequently, a positional relationship betweenthe suction nozzle 72 and the electronic component thus sucked and heldis detected. Based on the result of inspection which is input from theinspecting apparatus 200, then, the target mounting position of theelectronic component is changed from the position of a land to beusually used to the printing position of the solder paste and a shift ofthe suction nozzle 72 from the electronic component which is caused bythe recognized sucking attitude is corrected to mount the electroniccomponent on the circuit board 12.

The operation for changing a target mounting position and a correctingoperation depending on the recognized sucking attitude can be carriedout by causing the XY robot to have shift amounts in X and Y directionsas offsets and rotating the suction nozzle 72 through the motor 82 by ashift amount for a rotating component, for example.

A procedure for changing the target mounting position of the electroniccomponent from the position of the land to be usually used to theprinting position of the solder paste based on the result of inspectionwhich is input from the inspecting apparatus 200 will be described indetail with reference to a flow chart shown in FIG. 13.

First of all, the circuit board 12 is delivered into the printer 100 anda solder paste is printed corresponding to each land formed on thecircuit board 12 (S10). Then, the circuit board 12 is delivered from theprinter 100 and is delivered into the inspecting apparatus 200 in alatter stage.

Referring to FIG. 14 schematically showing the contents of inspection,in the inspecting apparatus 200, a land 14 formed on the circuit board12 and the solder paste 16 printed by setting the land 14 in a targetposition are illuminated by the light source 44 and an image is pickedup by the image pick-up camera 46. The image thus picked up is separatedinto a land portion 126 and a solder paste portion 128 based on adifference in a luminance of each pixel through an image processing andthe missed portion of the land which is interposed between the solderpaste 16 and the circuit board 12 and of which image is not picked up isreproduced by an interpolating process by using prepared land dataregistering the shape of the land. For example, it is possible toaccurately reproduce a complete shape of the land by precisely detectingthe feature of the shape of the land other than the missed portion (anedge component such as a corner portion or a side of which image ispicked up) and estimating the position of the feature of the residualshape from the position of the feature of the shape thus detected whilecarrying out collation with the shape of the land which is registered inthe land data.

Next, the position of the center of the land shape thus separated andreproduced is measured (S11). As shown in FIG. 15, center-of-gravitypositions O_(L1) (x₁, y₁) and O_(L2) (x₂, y₂) of the lands 14 a and 14 bof the circuit board 12 are measured by setting, as a referenceposition, any board mark 130 for alignment which is provided in thediagonal line position of the circuit board 12 (or an individual markprovided for another purpose). A middle point connecting thecenter-of-gravity positions O_(L1) and O_(L2) are set to a land centerpoint O_(L) (x_(L), y_(L)).

Similarly, a solder paste printing position is measured from theseparated solder paste portion 128 (S12). As shown in FIG. 16,center-of-gravity positions O_(C1) (x₃, y₃) and O_(C2) (x₄, y₄) of thesolder pastes 16 a and 16 b printed on the circuit board 12 aremeasured. A middle point connecting the center-of-gravity positionsO_(C1) and O_(C2) is set to a solder paste center point O_(C) (x_(C),y_(C)). Thus, the land center position O_(L) and the solder paste centerposition O_(C) are determined. Therefore, shift amounts α and β in the Xand Y directions are obtained from the center positions O_(L) and O_(C)(S13).

Next, the shift amounts α and β thus obtained are compared with apredetermined allowable value of a shift(S14). If the shift amounts αand β are equal to or greater than the allowable value of a shift, thereis a possibility that the shift might be caused in the direction ofrotation as shown in FIG. 17. Therefore, a shift amount θ in thedirection of rotation is measured (S15). The shift amount θ is obtainedby an equation (1), for example.θ=tan⁻¹{(y ₃ +y ₄)/(x ₃ −x ₄) }  (1)

If the shift amounts α and β are smaller than the allowable value of ashift, the measurement of the shift amount θ in the direction ofrotation is omitted to assume θ=o. Also in the case in which the amountsα and β are smaller than the allowable value of a shift, the shiftamount θ in the direction of rotation may be obtained positively.

By using the shift amounts α, β and θ in the X and Y directions and thedirection of rotation between the position of the land and the printingposition of the solder paste, the electronic component 18 is mounted byusing the printing position of the solder paste to be a reference asshown in FIG. 2 (S16). More specifically, the electronic component 18 ismounted by controlling the X-axis motor 98 a, the Y-axis motor 98 b, theZ-axis motor 98 c and the θ-axis motor 98 d (see FIG. 11) which aremounted on the XY robot and the attachment head in the electroniccomponent mounting apparatus 300 such that the central position of theelectronic component 18 is coincident with the central positions of thesolder pastes 16 a and 16 b printed with the shift amounts of α, β and θwith respect to the lands 14 a and 14 b.

The target mounting position can also be varied successively on theelectronic component mounting apparatus 300 side during the mounting ofthe electronic component, and furthermore, the mounting positionrecorded in the NC program 114 of the mounting data shown in FIG. 12 maybe changed, for example. Moreover, the target mounting position may bechanged to carry out 100% correction with respect to each of the shiftamounts of α, β and θ. Furthermore, the shift amount may be changed byan optional rate between 0 and 100% for the shift amount. In this case,a fine control can be carried out to make the best of the self-alignmenteffect that is changed on slightly conditions and the optimum mountingstate can be obtained.

According to the electronic component mounting method described above,the result of detection of the printing position, which is output at theprinting position detecting step, is subjected to a feed-forward controlto the mounting step. Consequently, it is possible to instantaneouslyset, as a solder paste printing position reference, the target mountingposition of the electronic component on the circuit board to be a objectfor detecting solder paste printing position. Moreover, theself-alignment effect in which the electronic component once mounted ismoved to a normal land position by the reflow process can be produced ata maximum and a bridge can be prevented from being generated by theunnecessary “extension wetting” of the solder over the side surface ofthe electronic component terminal also in the circuit board having asmall mounting interval between the electronic components, and it ispossible to maintain the quality of the circuit board which has beensubjected to the mounting to be high and to stably mount the electroniccomponent at a high density. Moreover, since an optimum target mountingposition can be set for each electronic component, the precision in themounting can be enhanced.

In the electronic component mounting method, the position of the land isnot measured but only the printing position of the solder paste may bedetected to mount the electronic component by setting the printingposition of the solder paste to be the target mounting position.

Next, description will be given to a second embodiment of the electroniccomponent mounting method according to the invention.

While the position of the land and the printing position of the solderpaste are detected every electronic component for each electroniccomponent to be mounted on the circuit board and the shift amountsthereof are obtained to change the mounting position of the electroniccomponent in the first embodiment, a shift amount between the positionof a land and the position of a printed solder paste is obtained for allthe electronic components to be mounted on the circuit board and anaverage value of the shift amount for each electronic component iscalculated to collectively change the mounting position of theelectronic component on the circuit board based on the average value ofthe shift amount thus obtained in the second embodiment.

A specific changing procedure will be described below. For example, inthe case in which N electronic components are to be mounted on thecircuit board, each shift amount is set in the following manner in orderof mounting for NC data to be mounting data.

-   -   Data 1: α₁, β₁, θ₁    -   Data 2: α₂, β₂, θ₂    -   Data 3: α₃, β₃, θ₃    -   . . .    -   Data N: α_(N), β_(N), θ_(N)

An X-direction correction value, a Y-direction correction value and aθ-direction correction value are set from the shift amounts by usingequations (2) to (4).X-direction correction value=(α₁+α₂+α₃+ . . . +α_(N))/N   (2)Y-direction correction value=(β₁+β₂+β₃+ . . . +β_(N))/N   (3)θ-direction correction value=(θ₁+θ₂+θ₃+ . . . +θ_(N))/N   (4)

The correction values in the equations (2) to (4) are applied to all theelectronic components to be mounted on the circuit board and themounting is carried out by collectively changing the target mountingposition. As compared with the case in which the mounting positions areindividually changed for the electronic components, consequently, theamount of a whole calculation process can be reduced and the speed ofthe mounting operation can be increased.

Next, description will be given to a third embodiment of the electroniccomponent mounting method according to the invention.

While the amount of the shift of the solder paste printed on the circuitboard from the land is averaged and the target mounting position ischanged in one way with respect to all the electronic components in thesecond embodiment, the circuit board is divided into the optional numberof blocks, and the average value of a shift amount is obtained for eachblock and the mounting position of the electronic component is changedfor each block by using the average value of each block thus obtained inthe third embodiment.

A pattern for dividing the circuit board into the optional number ofblocks includes a dividing pattern shown in FIG. 18, for example. FIG.18(a) shows an example in which the circuit board is divided annularlyinto regions from the peripheral edge of the circuit board toward acenter and FIG. 18(b) shows an example in which the circuit board isdivided into regions like a lattice. In the dividing pattern shown inFIG. 18(a), the shift amount of a central portion (region C) of thecircuit board is small and tends to be increased toward a peripheraledge portion (block A). In this case, the target mounting position ofthe electronic component is set by using a small correction value for asmall shift amount in the block C and a great correction value for alarge shift amount in the block A, respectively. In the dividing patternshown in FIG. 18(b), moreover, the shift amount is small in a cornerportion (for example, the block A) and tends to be increased apart fromthe corner portion. In this case, the target mounting position is set byusing a small correction value in the block A and a great correctionvalue in other blocks respectively.

More specifically, set shift amounts (correction values) αi, βi and θi(i is 1 to M) in the blocks are expressed in equations (5) to (7),wherein the number of region divisions (the number of blocks) isrepresented by M and the number of mounted components in each block isrepresented by Naj (j is 1 to M).αi=(αij+ . . . +αiMNaj)/Naj   (5)βi=(βij+ . . . +βiMNaj)/Naj (6)θi=(θij+ . . . +θiMNaj)/Naj   (7)

αij, βij and θij represent shift amounts for a jth electronic componentin a block i.

By individually setting the correction value to each block, thus, thetarget mounting position of a block having a small shift amount can beprevented from being greatly shifted by the influence of a block havinga large shift amount. Consequently, it is possible to carry out themounting over the circuit board with precision in uniform alignment.

Next, description will be given to a fourth embodiment of the electroniccomponent mounting method according to the invention.

In the embodiment, as shown in FIG. 19, various parameters such as theweight and shape of an electronic component to be mounted, the materialcomposition of a solder paste to be used, a friction property, aviscosity, a solder powder size, a melting point, a flux component (aresin base, an organism base and an inorganism base), a flux activity ora printing thickness are arranged in a table and a self-alignment ratiois assumed depending on the combination of the type of an electroniccomponent to be actually used and the material of the solder paste byutilizing the table. The self-alignment ratio represents an indexindicating, as a percentage, the degree of a shift from the center ofthe printed solder paste that self-alignment is effective. Based on theself-alignment ratio, the degree (for example, 50%, 80% or 100%) of theshift amount of the printing position of the solder paste to be utilizedas a correction value for setting a target mounting position is set.

While the parameter table for the solder paste is registered as thesolder data 124 in a part of mounting data as shown in FIG. 12, it isnot restricted but may have such a structure as to be registered inother data regions, for example, the NC program 114 and the arrayprogram 116. For the contents of registration, moreover, themanufacturer type name of a solder paste can also be set in addition toeach parameter. In this case, each characteristic parametercorresponding to the type name can be previously registered in the tableand can be collectively set automatically in the table. Consequently, awork for inputting the mounting data can be simplified considerably.

According to the embodiment, the correction value can be properlychanged for each mounting component depending on the combination of thetype of the electronic component to be used actually and the type of thesolder paste so that the electronic component to be mounted can obtain agreater self-alignment effect. Moreover, the correction value is set bydirectly reflecting the self-alignment effect. Consequently, precisionin component mounting can be enhanced still more.

Next, description will be given to a fifth embodiment of the electroniccomponent mounting method according to the invention.

In the embodiment, as shown in FIG. 20, a self-alignment effect isdetermined to some extent depending on the printing position of a solderpaste for the position of a land. Therefore, whether the printingposition of the solder paste is set to a target mounting position or theposition of the land is set to the target mounting position is selecteddepending on the shift state of the printing position of the solderpaste.

FIG. 20(a) shows a state in which the solder paste is printed with ashift from the centers of lands 14 a and 14 b. In this case, theself-alignment effect can be obtained sufficiently. FIG. 20(b) shows astate in which the solder paste is printed with a protrusion from thelands 14 a and 14 b. In this case, the solder paste is divided out ofthe land during reflow so that the self-alignment effect is reduced.

In the embodiment, the printing state of the solder paste is thusdetected so that the self-alignment ratio is assumed and the targetmounting position is determined depending on the self-alignment ratio.FIG. 21 is a flow chart showing the electronic component mounting methodaccording to the embodiment. First of all, the images of the positionand shape of a land are picked up and recognized by an inspectingapparatus 200 (S20). Moreover, the printing position and shape of thesolder paste are recognized (S21). From these results of recognition, aself-alignment ratio is decided (S22). If the self-alignment ratio ishigh, the printing position of the solder paste is set to a targetmounting position (S23). If the self-alignment ratio is low, theposition of the land is set to the target mounting position (S24).

Consequently, in the case in which the print shift of the solder pasteis great, it is possible to prevent an electronic component from beingmounted in a position in which the self-alignment effect cannot besufficiently obtained and being fixed with a shift after a reflowprocess.

Next, description will be given to a sixth embodiment of the electroniccomponent mounting method according to the invention.

In the embodiment, in the case in which the printing position of asolder paste is set to a target mounting position to mount an electroniccomponent, it is supposed that the adjacent electronic componentsinterfere with each other as shown in FIG. 22. By previously obtainingthe presence of the interference through a calculation before themounting, the generation of a failure in mounting can be prevented.

More specifically, the mounting position of the electronic componentrecorded in an NC program 114 provided in the mounting data shown inFIG. 12 and the contour of the electronic component based on a componentsize recorded in a component library 118 are obtained and it is decidedwhether or not the contour in the mounting position obtained aftercorrecting the shift amount of the printing position of the solder pasteand the contour of the adjacent components interfere with each other. Ifthere is no interference, the mounting process is exactly carried out.If there is the interference, the component is not mounted. If there isthe interference, moreover, the mounting position may be corrected tosuch a position that the electronic components do not interfere witheach other, thereby carrying out the mounting. In this case, it ispossible to prevent a recovery process from being carried out due to thestop of the mounting operation for the electronic component. Thus, themounting step can be executed more quickly. For the correction of themounting position, it is also possible to use a method of successivelychanging a target mounting position during the mounting to be carriedout or a method of rewriting the mounting position of the NC program 114to carry out the mounting.

Consequently, the generation of a mounting failure can be prevented andthe productivity of a circuit board can be prevented from beingdeteriorated.

Next, description will be given to a variant of an electronic componentmounting system for implementing the electronic component mountingmethod according to each embodiment described above.

FIG. 23 is a view showing an example of the structure of the electroniccomponent mounting system according to a first variant. In the variant,there is provided a structure using a solder paste printing apparatus102 having a inspecting function integrating the function of the solderpaste printing apparatus 100 with that of the inspecting apparatus 200.In this case, the solder paste printing apparatus 102 can be implementedby using the board recognizing camera 36 or the mask recognizing camera38 shown in FIG. 6 for detecting the position of a land and the printingposition of a solder paste, for example. Moreover, a inspecting portionmay be added separately. With such a structure, an installation spacecan be reduced and a process for delivering a circuit board can besimplified so that the process can be carried out more quickly.

FIG. 24 is a view showing an example of the structure of the electroniccomponent mounting system according to a second variant. In the variant,there is provided a structure using an electronic component mountingdevice 302 having a inspecting function integrating the function of theinspecting apparatus 200 with that of the electronic component mountingapparatus 300. In this case, the electronic component mounting apparatus302 can be implemented by using a board recognizing camera for detectinga board mark for alignment in order to detect the position of a land andthe printing position of a solder paste, for example. Moreover, ainspecting unit may be added separately. Such a structure can alsoreduce an installation space and simplify a process for delivering acircuit board so that the process can be carried out more quickly.

FIG. 25 is a view showing an example of the structure of the electroniccomponent mounting system according to a third variant. In this case, asolder paste printing apparatus 100, a inspecting apparatus 200 and anelectronic component mounting apparatus 300 are connected to a hostcomputer 140 respectively and each device is generally controlled by thehost computer 140. The result of inspection of a solder paste printingposition shift sent from the inspecting apparatus 200 is input to thehost computer 140, and the host computer 140 outputs the input positionshift information to the electronic component mounting apparatus 300 tocarry out a feedforward control. According to such a structure, theelectronic component mounting system can be generally managed. Inaddition, also in the case in which a circuit board manufacturing lineis formed by a plurality of mounting systems, they can be easilyconnected to carry out the control.

While the mounting data (mounting program) are created over theelectronic component mounting apparatus 300 in the electronic componentmounting system described above, the same data may be created by anotherexternal device (a mounting data creating device) to be connected to theelectronic component mounting apparatus 300 through a communication lineor a recording medium. In this case, the mounting data created by themounting data creating device are fetched into the electronic componentmounting apparatus 300 so that the mounting operation can be carriedout. Also during the mounting operation of the electronic componentmounting apparatus 300, the mounting data can be created. Therefore, aworkability for data creation can be enhanced and the operatingefficiency of producing equipment can be increased.

Moreover, while the electronic component mounting apparatus 300 has sucha structure that the circuit board to mount the electronic componentthereon is fixed and a transfer head provided with an attachment head ismoved over the circuit board to carry out the mounting operation, theinvention is not restricted thereto but the electronic componentmounting method according to the invention can be similarly applied toan electronic component mounting apparatus including a rotary head asshown in FIGS. 26 and 27, for example.

FIG. 26 is a view showing the appearance of the electronic componentmounting apparatus including the rotary head and FIG. 27 is a schematicsectional view showing the rotary head for illustrating the operation ofthe rotary head. An electronic component mounting apparatus 400 mainlyhas a component feeding portion 150 for continuously feeding anelectronic component, a rotary head 152 for holding the electroniccomponent in the predetermined component feeding position of thecomponent feeding unit 150 and for mounting the electronic component onthe circuit board, and an X-Y table 154 for positioning the circuitboard. Consequently, the circuit board fed from a board delivery-inportion 156 is mounted on the X-Y table 154 and the electronic componentsent from the component feeding unit 150 is held by the rotary head 152,and a proper correcting process is then carried out to mount theelectronic component on the circuit board. The circuit board having thecomponent mounted thereon is delivered from the X-Y table 154 to a boarddelivery-out portion 158.

In a compartment feeding unit 10, a plurality of component feedingmembers 160 accommodating a large number of electronic components arearranged in a vertical direction on a paper as shown in FIG. 27 and acompartment feeding member 160 is moved in the direction of thearrangement, thereby feeding a desirable electronic component to acomponent feeding position.

The X-Y table 154 is provided movably between the board delivery-in unit156 and the board delivery-out unit 158, is moved to a position to beconnected to the board delivery path of the board delivery-in unit 156to receive the circuit board which has not attached the component, andfixes the circuit board and is moved to the component mounting positionof the rotary head 152. Then, the movement of the circuit board 12corresponding to the mounting position of each electronic component isrepeated. When the attachment of the component is completed, the XYtable 154 is moved to a position to be connected to the boarddelivery-out unit 158 and feeds the circuit board 12 to the boarddelivery-out unit 158.

The rotary head 152 includes a plurality of attachment heads 162 forsucking an electronic component, a rotating frame member 164 to berotated by supporting the attachment head 162 on a peripheral surfacevertically movably, and an intermittent rotating device 168 for indexrotating the rotating frame member 164.

An attachment head 262 is continuously rotated and moved from thecomponent feeding position of the component feeding unit 150 to acomponent attachment position on the opposite side thereof by therotation of the rotating frame member 164, falls down in the componentfeeding position of the component feeding unit 150 to adsorb theelectronic component, and recognizes the sucking attitude of theelectronic component in a certain component recognition position of thecomponent recognizing device to fall down in the component attachmentposition, thereby attaching the electronic component onto the circuitboard 12.

The electronic component mounting method according to the embodiment canalso be applied to the electronic component mounting apparatus 400including such a rotary head and the same effects can be obtained.

Description will be given to the result of a difference in aself-alignment effect based on a difference between the mountingposition of an electronic component and the printing position of asolder paste.

FIG. 28 shows a result of comparison of the self-alignment effects ontwo conditions. FIG. 28(a) shows a state in which a solder paste isprinted on a land position reference and an electronic component ismounted in a position shifted by Δ1, FIG. 28(b) shows a state in whichthe solder paste is printed with a shift from the position of the landby Δ1 and the electronic component is mounted in the printing positionof a solder paste, and FIG. 28(c) is a graph showing a self-alignmentratio obtained in FIGS. 28(a) and (b). An axis of abscissa in the graphindicates an average value obtained by a shift in each of X and Ydirections, and the used electronic component is referred to as a “0603chip” having a size of 0.6 mm×0.3 mm. Moreover, the self-alignment ratiorepresents a probability of a return to a position within ±10 μm from aland center to be a reference.

As shown in the graph of FIG. 28(c), in the case (a) in which only themounting position of the electronic component is shifted, theself-alignment ratio is considerably reduced with an increase of theshift amount Δ1 as compared with the case in which the mounting iscarried out on the printing position reference. For example, when theshift amount Δ1 is 50 μm, the self-alignment ratio is reduced to 70% inthe (a), while the self-alignment ratio is 90% in the case (b).Consequently, it is apparent that the electronic component is mounted inthe printing position of the solder paste so that a greaterself-alignment effect can be expected than that in the case in which theelectronic component is mounted in the position of the land.

According to the electronic component mounting method and apparatus inaccordance with the invention, the printing position of the solder pasteof the circuit board is detected at the printing position detecting stepand the electronic component is mounted by using the printing positionof the solder paste thus detected as a reference at the mounting step.Consequently, when the solder paste is molten by a reflow process, aself-alignment effect of returning the electronic component to theposition of a land by the fluidization of the solder paste can bemaintained to be great, and the electronic component can be reliablyfixed into the position of the land even if the printing position of thesolder paste is shifted from the position of the land. Also in the casein which the mounting interval of the electronic component is small,moreover, it is possible to enhance precision in the mounting positionof the electronic component by effectively utilizing the self-alignmenteffect.

Moreover, the electronic component mounting system in accordance withthe invention includes a printing position detecting device fordetecting a printing position of the solder paste of the circuit board,and an electronic component mounting apparatus for mounting anelectronic component based on a result of detection of the printingposition. The electronic component is mounted by using the printingposition of the solder paste as a reference. Consequently, theself-alignment effect of returning the electronic component into theposition of the land can be maintained to be great and the electroniccomponent can be reliably fixed in the position of the land after thereflow process of the circuit board.

According to the electronic component mounting data creating method inaccordance with the invention, furthermore, the mounting data forcarrying out a mounting operation based on the electronic componentmounting method can be created easily with reference to a previouslyregistered table through the electronic component mounting apparatus orthe mounting data creating device connected thereto.

According to the mounting data creating device in accordance with theinvention, moreover, the mounting data for mounting the electroniccomponent on the circuit board are created irrespective of theelectronic component mounting apparatus, and the electronic componentmounting apparatus is subsequently caused to fetch the mounting datathus created. Consequently, even if the electronic component mountingapparatus is carrying out the mounting operation, the mounting data canbe created. Thus, a workability for data creation can be enhanced andthe operating efficiency of producing equipment can be increased.

According to the program in accordance with the invention, the programrecording mounting data for mounting an electronic component on acircuit board based on the electronic component mounting method is usedfor an electronic component mounting apparatus. Consequently, it ispossible to mount the electronic component with the self-alignmenteffect enhanced.

1. An electronic component mounting apparatus for mounting an electroniccomponent comprising: a mounting means for mounting the electroniccomponent on the circuit board on which is formed a land and printed asolder paste by referring to a printing position of the solder paste asa reference.
 2. The electronic component mounting apparatus according toclaim 1, further comprising: a mounting data creating device forcreating a data utilized for mounting the electronic component on thecircuit board by the mounting means.
 3. An electronic component mountingsystem for mounting an electronic component comprising: a printingposition detecting device for detecting a printing position of a solderpaste on a circuit board on which a land is formed and the solder pasteis printed, and an electronic component mounting apparatus for mountingan electronic component on the circuit board by referring the detectedprinting position of said solder paste.
 4. The electronic componentmounting system according to claim 3, further comprising: a solder pasteprinting apparatus for printing the solder paste on the circuit board bysetting a position of the land as a target position.
 5. The electroniccomponent mounting system according to claim 4, wherein said printingposition detecting device is provided in the solder paste printingapparatus.
 6. The electronic component mounting system according toclaim 3, wherein the printing position detecting device is provided inthe electronic component mounting apparatus.
 7. The electronic componentmounting system according to claim 3, further comprising: a hostcomputer connected to both of the printing position detecting device andthe electronic component mounting apparatus through a communicationline, and wherein said host computer receives a detected printingposition from the printing position detecting device and transmits afeed-forward signal to the electronic component mounting apparatus. 8.The electronic component mounting system according to claim 4, furthercomprising: an inspecting apparatus for inspecting states of saidprinted solder paste and said land formed on said circuit board.
 9. Theelectronic component mounting system according to claim 8, wherein saidprinting position detecting device is provided in said inspectingapparatus.